I'm writing an application with a business requirement of reconnecting a dead db connection to Sybase through the syb_err_handler() error handler routine.

In the past, I would just run $dbh->DBDEAD() just prior to running the queries. If the connection was dead, I would just reconnect and run the query (plus any initialization db routines).

The syb_err_hander() can easily catch a dead connection but calling $dbh->connect() in the error handler fails

$ ./test_sybase ERROR: Connection dropped ct_config(CS_SET, CS_LOGIN_TIMEOUT) failed at /usr/lib64/perl5/site_pe +rl/5.8.8/x86_64-linux-thread-multi/DBD/Sybase.pm line 94. ct_config(CS_SET, CS_TIMEOUT) failed at /usr/lib64/perl5/site_perl/5.8 +.8/x86_64-linux-thread-multi/DBD/Sybase.pm line 94. ct_con_alloc failed at /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-t +hread-multi/DBD/Sybase.pm line 94. ERROR: unable to connect to SISDBA

Has anyone done this? I'm starting to think that this can't be done through the error handler of DBD::Sybase

#!/usr/bin/perl use strict; use warnings; use lib "/home/jfroebe/lib"; use DBI; use File::Basename; our $SYBDBA_login = 'login'; our $SYBDBA_password = 'password'; our $dbh = connect_dbms(); sub report_err { my $msg = shift; my $type = shift; if ($type eq 'error') { print "ERROR: $msg\n"; } else { print "MSG: $msg\n"; } } sub syb_err_handler { my($err, $sev, $state, $line, $server, $proc, $msg, $sql, $err_typ +e) = @_; my %ignore_errors = map { $_, 1 } (6, 183, 208, 2056, 2057, 14024, + 17001); if ($err == 151 || $err == 50 || $err == 60) { report_err("Connection dropped", "error"); for (my $attempt = 0; $attempt < 10; $attempt++) { if ($dbh = connect_dbms()) { report_err("Reconnected", "error"); return 0; } sleep 2; } return 1; } elsif ($err == 63 || ($err == 4 && $sev == 5) ) { report_err("Connection timed out", "error"); return 1; } elsif ($ignore_errors{$err}) { # ignore return 0; } print "error: $err, $sev, $state : $msg\n"; return 1; } sub connect_dbms { my $script = basename($0); if ($dbh = DBI->connect("dbi:Sybase:server=SISDBA;loginTimeout=10; +timeout=30;scriptName=$script;encryptPassword=1;tdsLevel=CS_TDS_50;ch +arset=iso_1", $SYBDBA_login, $SYBDBA_password, { PrintError => 0, Rai +seError => 0, syb_err_handler => \&syb_err_handler } )) { return $dbh; } report_err("unable to connect to SISDBA", "error"); return; } sub syb_loop { my $query = "exec sp_helpdb"; for (my $i = 0; $i < 10000; $i++) { my $array_ref = $dbh->selectall_arrayref($query); } } syb_loop();

Update:

I received an email from Michael Peppler, the creator/maintainer of DBD::Sybase. In it, he says that this is a limitation of Sybase's OpenClient CT-Library not DBD::Sybase.

The error handler is called by Sybase's ct_callback() function. Sybase has restricted what CT-Library calls that can be made. Apparently while ct-connect() can be called, memory allocation of the connection will be disallowed.

I'm opening a number of feature requests with Sybase to make reconnecting, when the connection dies, easier to do.

Jason L. Froebe

Team Sybase member

No one has seen what you have seen, and until that happens, we're all going to think that you're nuts. - Jack O'Neil, Stargate SG-1


In reply to DBD::Sybase - How to reconnect through err_handler by jfroebe

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